Routine neuroimaging with computerization tomography (CT) or magnetic resonance imaging (MRI) in HIV infection is useful for identifying generalized atrophy and structural lesions such as intracranial infections or tumors. In the absence of such lesions, qualitative CT or MRI is not sufficiently sensitive to evaluate the transition from HIV infection with normal cognitive function to minor or major cognitive impairment. Functional MRI (FMRI) is a novel neuroimaging tool which provides maps of human brain activation with high spatial and temporal resolution. The technique is a non-invasive assessment of changes in regional cerebral blood flow in response to a specific cognitive task. Functional neuroimaging may detect subtle alterations in neurological function before clinical and structural abnormalities develop. Another major advantage of fMRI is that it is non-invasive, requires no radioisotopes or ionizing radiation, and is repeatable. This study evaluates the fMRI activation pattern in response to a test of psychomotor speed in HIV- infected patients and HIV-controls. Subjects with psychomotor slowing consistent with early HIV dementia and HIV-controls will be selected. The cognitive paradigm chosen for investigation is psychomotor-function and its putative subcomponents. the subcomponents of principal interest include executing a cognitive operation and performance of a motor act. To investigate the functional integrity of these subcomponents in fMRI, we will perform a time course analysis of cerebral blood oxygenation/flow changes during performance of "baseline" and "activated" cognitive tasks for that given subcomponent.